Abrasive surface and method of making same



Oct. 2, 1928.

C. G. FINK ET AL ABRASIVE SURFACE AND METHOD OF MAKING SAME Filed March14, 1927 ATT0 EYS Patented Oct. 2, 1928.

UNITED STATES PATENT, OFFICE.

COLIN G. FINK AND ARTHUR H. KOPP, OF NEW YORK, N. Y., ASSIGNORS TOAMERICAN ABRASIVE METALS QOMPANY, A CORPORATION OF NEW YORK.

- ABBASIVE SURFACE AND METHOD OF MAKING SAME.

Application filed March 14, 1927. Serial No. 175,353.

The invention relates generally to articles larly to articles having abody of metal and a resistant surface formed by embedding therein hardmineral or wear-resistin elements, such as corundum, emery, an the Awell known method of making articles adapted to resist abrasion, suchfor example, as stair treads, conduits for dredging pumps, ashconveyors, and the like, consists in forming a mold, placing a layer ofwear-resist, ing elements, such as grains of carborundum, corundum,alundum, emery, or the like, upon a surface of the mold adapted to shapea surface of the article to be made, and pouring molten metal into themold. The resulting product is an article of the shape or form desiredto suit the particular purpose, as a stair tread, with a body of metaland a tread surface in which are embedded the emery. It is importantthat these grains of the wear-resisting material should be firmly andclosely gripped by the surrounding metal in which they are embedded,because if any of the grains should be separated from. their metal base,due to the rough usage to which the article is subjected, the surfacethus bared of the protecting grains would be speedily worn away, andthus other adjacent grains would also be rendered liable to be separatedfrom their metal bed.

The present invention, therefore, has for an object to provide anarticle of the character described which will be proof against the lossof the wear-resisting grains, and the invention also includes within itspurview the method of producing such articles.

In the accompanying drawings, which are referred to herein and form parthereof,

Fig. l is a cross-section of a mold adapted to produce a stair-treadhaving the charac-. teristics of the invention;

Fig. '2 is a perspective view of a "stairtread produced in such mold inaccordance with the method of the invention; and

Fig. 3 shows some of the grains of the wear-resisting material, preparedaccording to the invention, to be placed in said mold and incorporatedin the surface of the article.

An article of the character described havmg a wear-resistant surface mayhave a body adapted to meet the requirements of the particular use towhich the article is to be put. In a stair-tread, for example, the bodymaybe of a metal, as iron, which has the required strength and rigidityfor its purpose and which can be cast into the deslred form. As has beenstated, however, in order to make for the highest efiicienc the materialin which the grains of wear-resistmg material are embedded should be ofsuch a nature as to cling closely to the grains and grip3 them in a firmand enduring embrace. ecause of their peculiar character- 1st1cs,however, the grains of wear-resisting material mentioned do not lendthemselves readily to the described close embrace by certain materialsotherwise eminently suitable to form the body of the article in whichthe grains are to be embedded, as, for instance, iron in the castingprocess described. The invention, therefore, contemplates providing ameans and method for bringing about this desired afiinity between thegrains of wear-resisting material and the material formlng the body ofthe article, as the cast iron. This is accomplished by interposingbetween each grain and the body of the article a material which willadhere closely to the grain and at the same time combine with the bodyof the article, said material being of such nature that, when sointerposed and combined, a secure anchorage for the grain will beprovided. Hence, accordingto the preferred way of carrying out theinvention, the grains of wear-resisting material before being placed inthe mold are coated with a metal which has a lower melting point than,and which will form at such lower temperature a localized hard alloywith, the iron, for example, forming the body of the article. A suitablemetal for this purpose is tin and although tin is soft, it has beenfound that a thin coating of tin on the grains will form a localizedhard alloy with the iron of the body of the article and so secure theains from disturbance. A simple way 0 providing the grains with thisthin coating is to use friction, and therefore the grains with surfacespreferably roughened by fused alkali are placed in a drum with a supplyof small pieces of tin and tumbled until they are properly coated. Thegrains are now ready to be placed in the mold.

Referring now to the drawings in detail, there is shown in Fig. 1 a mold4, comprising a drag 5 and 00 e 6 which are formed to mold a stair-tree7 which will be here described, together with the method of making thesame, to illustrate the invention. On a surface 8 of the mold 4, whichsurface is adapted to shape the resistant surface of the tread 7, isplaced a layer of rains 10 of emei These grains 10, as s own in Fig. 3,ave previously been provided by the tumbling process with a thin coatingof tin. Thru the gate 11 of the mold the molten iron is poured and flowsover and about the grains 10 and thus form'the body 12 of the tread withits resistant surface 13, as shown in Fig. 2. As the molten ironsurrounds the grains, the iron will form with said coating a localizedthin, hard alloy which will wet, or cling closel' to the surfaces of thegrains, which wil now be securely embedded in the surface of the tread.Other articles adapted to resist abrasion may be made in a similar way.

The invention in its broader aspects is not limited to the particularmetals or alloy referred to nor to the particular order or sequence ofsteps by which the method of making the article is carried out, asdifferent metals may be used and the order of the successive steps ofthe method changed without departing from the main principles of theinvention or sacrificing its chief advanta- 5.

e claim:

1. An article adapted to resist abrasion comprising a base of castmetal, grains of wear-resisting material embedded in the surface of saidbase, and a localized metal alloy immediately surrounding each of saidgrains, the remainder of said base being free of said alloy.

2. An article adapted to resist abrasion comprising a base ofcast metal,rains of wear-resisting material embedde in the surface of said base,and a localized thin metal alloy immediately surrounding each of saidgrains, the remainder of said base being free of said aHoy.

3. An article adapted to resist abrasion comprising a base of castmetal, grains of wear-resisting material embedded in the surface of saidbase, and a localized metal alloy immediately surrounding each of saidgrains, the said alloy being composed of the metal of the body of thebase and a metal having a lower melting point than the said body metal,the remainder of said base being free of said alloy.

4. An article adapted to resist abrasion comprising a base of castmetal, grains of wear-resistin material embedded in the surface of saidbase, and a localized alloy of tin and iron immediately surrounding eachof said grains, the remainder of sai base being free of said alloy.

An article adapted to resist abrasion comprising a base of cast ironains of wear-resisting material embed e in the surface of said base, anda localized alloy of tin with the iron of the base immediatelysurrounding each of said grains, the remainder of said base being freeof said alloy.

6. An article adapted to resist abrasion comprising a base of cast iron,aim of wear-resisting material embedde in the surface of said base, anda localized thin alloy of tin with the iron of the base immediatelysurroundin each of said grains tllile remainder of said ase being freeof a oy.

7. The method of producin an article adapted to resist abrasion, whicmethod includes forming a mold for the article, applying a coatin ofmetal to grains of wear resisting material, distributing a layer of saidreviously coated grains on a surface of said mold adapted to she. asurface of said article, and pouring mo ten metal into said mold.

8. The method of producing an article adapted to resist abrasion, whichmethod includes forming'a mold for the article, applying to grains ofwear resisting material a coating of metal having a lower melti andalloying point than that of the metfi forming the body of said article,distributing a layer of said reviousl coated grains on a surface of saidmold a apted to shape a surface ofsaid article, and pouring molten metalinto said mold. I

9. The method of producin an article adapted to resist abrasion, whicmethod includes forming a mold for the article, ap-

plying a coating of'tin to individual ains of wear resisting material,distributing a layer of said previously individually coated grains on asurface of said mold adapted to shape a surface of said article, andpouring molten metal into said mold.

10. The method of producing an article ada ted to resist abrasion, whichmethod inclu es forming a mold for the article, applying to grains ofwear resisting materialacoating of metal adapted to cling closely to theindividual grains and havin a lower alloying and melting point than-t atof the metal forming the body of said article, distributing a layer ofsaid reviousl coated grains on a surface of sai mold a apted to shape asurface of said article, and pouring molten adapted to shape a surfaceof said article,

and pouring molten iron into said mold.

12. The method of producing an article adapted to resist abrasion, whichmethod aeegwo 3 includes forming a mold for the articl apto shape asurface of saidarticle grains of plying mechanically a thin coating 0?tin wear-resisting material, said grains first havto rains of emery,distributing a laer of ing their surfaces roughened by fused alkali saigrains on asurface of said mold a apted. and then coated with metal, andpouring 5 to shape a surface of saidarticle, and. pourlt m t l int idld, ing m l ll iI'O I n d m ldtestimony whereof, we have aed our 13. Themethod of producing an article signatures hereto.

adapted to resist abrasion, which method in- I v eludes forming a moldfor the article, dis- C LN G. F1.

tributing on a surface of said mold adapted f'=' J i' H, KOPP.

